Question

(b) A 20 kV, 50 Hz busbar supplies two loads A and B. The fault level on the busbar is 100 MVA. Load A absorbs 2 MW at unity p.f. and load B is an 8 MVAr capacitor bank. It is proposed to connect a 6-pulse rectifying load that draws a fundamental current of 500 A from the busbar. Table Q1(b) below lists the harmonic currents up to the 13th drawn by the rectifier as a percentage of the fundamental current. Table Q10) Harmonic 13 Number %of Fundamental 14.3 9.097.69 Determine the level of the 5th harmonic voltage on the 20 kV busbar after the connection of the rectifier. Express this voltage as a percentage of the busbar fundamental voltage [10 marks]

Answer 1